Refactor core calculation out of buck / boost converters (#407)

This makes the core component calculations more unit-testable and
unifies the buck-boost converter (as well as allowing other
variations-on-a-theme converters like forward-buck-reverse-boost as with
some NVDC battery chargers with OTG with less code duplication)

Changes the boost inductor calculation to avoid double-counting output
tolerance. The inductance formula appears monotonic.

Core infrastructural changes:
- Refactor NumLikeExpr types (IntExpr, FloatExpr, RangeExpr) to
centrally define castable-types and properly return NotImplemented on a
type it cannot handle. This cleanly handles promotion of FloatLike /
IntLike types to Range types.
- Add hull and intersect to Range

Follow-on PRs will add coupled current/inductance support (#405) and the
MP2722 converter which this is building towards.

Author: ducky64

edg/abstract_parts/AbstractPowerConverters.py

@@ -0,0 +1,88 @@
+import unittest
+
+from .AbstractPowerConverters import BuckConverterPowerPath, BoostConverterPowerPath
+from ..core import Range
+
+
+class BuckConverterCalculationTest(unittest.TestCase):
+    def test_buck_converter(self):
+        values_ref = BuckConverterPowerPath.calculate_parameters(
+            Range.exact(5), Range.exact(2.5), Range.exact(100e3), Range.exact(1),
+            Range.exact(0.1), 0.01, 0.001,
+            efficiency=Range.exact(1)
+        )
+        self.assertEqual(values_ref.dutycycle, Range.exact(0.5))
+        # validated against https://www.omnicalculator.com/physics/buck-converter
+        self.assertEqual(values_ref.inductance, Range.exact(125e-6))
+
+        # test that component values are calculated for worst-case conversion
+        values = BuckConverterPowerPath.calculate_parameters(
+            Range(4, 5), Range(2.5, 4), Range.exact(100e3), Range.exact(1),
+            Range.exact(0.1), 0.01, 0.001,
+            efficiency=Range.exact(1)
+        )
+        self.assertEqual(values_ref.inductance, values.inductance)
+        self.assertEqual(values_ref.input_capacitance, values.input_capacitance)
+        self.assertEqual(values_ref.output_capacitance, values.output_capacitance)
+
+    def test_buck_converter_example(self):
+        # using the example from https://passive-components.eu/buck-converter-design-and-calculation/
+        values = BuckConverterPowerPath.calculate_parameters(
+            Range.exact(12 + 0.4), Range.exact(3.3 + 0.4), Range.exact(500e3), Range.exact(1),
+            Range.exact(0.35), 1, 0.0165,
+            efficiency=Range.exact(1)
+        )
+        self.assertAlmostEqual(values.dutycycle.upper, 0.298, places=3)
+        self.assertAlmostEqual(values.inductance.upper, 14.8e-6, places=7)
+
+        # the example uses a ripple current of 0.346 for the rest of the calculations
+        values = BuckConverterPowerPath.calculate_parameters(
+            Range.exact(12 + 0.4), Range.exact(3.3 + 0.4), Range.exact(500e3), Range.exact(1),
+            Range.exact(0.346), 1, 0.0165,
+            efficiency=Range.exact(1)
+        )
+        self.assertAlmostEqual(values.inductor_peak_currents.upper, 1.173, places=3)
+        self.assertAlmostEqual(values.output_capacitance.lower, 5.24e-6, places=7)
+
+    def test_boost_converter(self):
+        values_ref = BoostConverterPowerPath.calculate_parameters(
+            Range.exact(5), Range.exact(10), Range.exact(100e3), Range.exact(1),
+            Range.exact(0.1), 0.01, 0.001,
+            efficiency=Range.exact(1)
+        )
+        self.assertEqual(values_ref.dutycycle, Range.exact(0.5))
+        # validated against https://www.omnicalculator.com/physics/boost-converter
+        self.assertEqual(values_ref.inductance, Range.exact(250e-6))
+
+        # test that component values are calculated for worst-case conversion
+        values = BoostConverterPowerPath.calculate_parameters(
+            Range(5, 8), Range(7, 10), Range.exact(100e3), Range.exact(1),
+            Range.exact(0.1), 0.01, 0.001,
+            efficiency=Range.exact(1)
+        )
+        self.assertEqual(values_ref.inductance, values.inductance)
+        self.assertEqual(values_ref.input_capacitance, values.input_capacitance)
+        self.assertEqual(values_ref.output_capacitance, values.output_capacitance)
+
+    def test_boost_converter_example(self):
+        # using the example from https://passive-components.eu/boost-converter-design-and-calculation/
+        # 0.4342A ripple current from .35 factor in example converted in output current terms
+        values = BoostConverterPowerPath.calculate_parameters(
+            Range.exact(5), Range.exact(12 + 0.4), Range.exact(500e3), Range.exact(0.5),
+            Range.exact(0.4342), 1, 1,
+            efficiency=Range.exact(1)
+        )
+        self.assertAlmostEqual(values.dutycycle.upper, 0.597, places=3)
+        self.assertAlmostEqual(values.inductance.upper, 13.75e-6, places=7)
+
+        # the example continues with a normalized inductance of 15uH
+        values = BoostConverterPowerPath.calculate_parameters(
+            Range.exact(5), Range.exact(12 + 0.4), Range.exact(500e3), Range.exact(0.5),
+            Range.exact(.4342*13.75/15), 0.01, 0.06,
+            efficiency=Range.exact(1)
+        )
+        self.assertAlmostEqual(values.dutycycle.upper, 0.597, places=3)
+        self.assertAlmostEqual(values.inductance.upper, 15.0e-6, places=7)
+        self.assertAlmostEqual(values.inductor_peak_currents.upper, 1.44, places=2)
+        # the example calculation output is wrong, this is the correct result of the formula
+        self.assertAlmostEqual(values.output_capacitance.lower, 9.95e-6, places=7)

edg/abstract_parts/test_switching_converters.py

@@ -173,6 +173,8 @@ def then_else(self, then_val: IteType, else_val: IteType) -> IteType:
 class NumLikeExpr(ConstraintExpr[WrappedType, NumLikeCastable], Generic[WrappedType, NumLikeCastable]):
   """Trait for numeric-like expressions, providing common arithmetic operations"""
 
+  _CASTABLE_TYPES: Tuple[Type[NumLikeCastable], ...]  # NumLikeCastable for use in ininstance(), excluding self-cls
+
   @classmethod
   @abstractmethod
   def _to_expr_type(cls: Type[NumLikeSelfType],
@@ -209,28 +211,44 @@ def __mul_inv__(self: NumLikeSelfType) -> NumLikeSelfType:
     return self._create_unary_op(self, NumericOp.invert)
 
   def __add__(self: NumLikeSelfType, rhs: NumLikeCastable) -> NumLikeSelfType:
-    return self._create_binary_op(self, self._to_expr_type(rhs), NumericOp.add)
+    if isinstance(rhs, self._CASTABLE_TYPES) or isinstance(rhs, self.__class__):
+      return self._create_binary_op(self, self._to_expr_type(rhs), NumericOp.add)
+    return NotImplemented
 
   def __radd__(self: NumLikeSelfType, lhs: NumLikeCastable) -> NumLikeSelfType:
-    return self._create_binary_op(self._to_expr_type(lhs), self, NumericOp.add)
+    if isinstance(lhs, self._CASTABLE_TYPES) or isinstance(lhs, self.__class__):
+      return self._create_binary_op(self._to_expr_type(lhs), self, NumericOp.add)
+    return NotImplemented
 
   def __sub__(self: NumLikeSelfType, rhs: NumLikeCastable) -> NumLikeSelfType:
-    return self.__add__(self._to_expr_type(rhs).__neg__())
+    if isinstance(rhs, self._CASTABLE_TYPES) or isinstance(rhs, self.__class__):
+      return self.__add__(self._to_expr_type(rhs).__neg__())
+    return NotImplemented
 
   def __rsub__(self: NumLikeSelfType, lhs: NumLikeCastable) -> NumLikeSelfType:
-    return self.__neg__().__radd__(self._to_expr_type(lhs))
+    if isinstance(lhs, self._CASTABLE_TYPES) or isinstance(lhs, self.__class__):
+      return self.__neg__().__radd__(self._to_expr_type(lhs))
+    return NotImplemented
 
   def __mul__(self: NumLikeSelfType, rhs: NumLikeCastable) -> NumLikeSelfType:
-    return self._create_binary_op(self, self._to_expr_type(rhs), NumericOp.mul)
+    if isinstance(rhs, self._CASTABLE_TYPES) or isinstance(rhs, self.__class__):
+      return self._create_binary_op(self, self._to_expr_type(rhs), NumericOp.mul)
+    return NotImplemented
 
   def __rmul__(self: NumLikeSelfType, lhs: NumLikeCastable) -> NumLikeSelfType:
-    return self._create_binary_op(self._to_expr_type(lhs), self, NumericOp.mul)
+    if isinstance(lhs, self._CASTABLE_TYPES) or isinstance(lhs, self.__class__):
+      return self._create_binary_op(self._to_expr_type(lhs), self, NumericOp.mul)
+    return NotImplemented
 
   def __truediv__(self: NumLikeSelfType, rhs: NumLikeCastable) -> NumLikeSelfType:
-    return self.__mul__(self._to_expr_type(rhs).__mul_inv__())
+    if isinstance(rhs, self._CASTABLE_TYPES) or isinstance(rhs, self.__class__):
+      return self.__mul__(self._to_expr_type(rhs).__mul_inv__())
+    return NotImplemented
 
   def __rtruediv__(self: NumLikeSelfType, lhs: NumLikeCastable) -> NumLikeSelfType:
-    return self.__mul_inv__().__mul__(self._to_expr_type(lhs))
+    if isinstance(lhs, self._CASTABLE_TYPES) or isinstance(lhs, self.__class__):
+      return self.__mul_inv__().__mul__(self._to_expr_type(lhs))
+    return NotImplemented
 
   @classmethod
   def _create_bool_op(cls,
@@ -245,23 +263,35 @@ def _create_bool_op(cls,
     return BoolExpr()._bind(BinaryOpBinding(lhs, rhs, op))
 
   def __ne__(self: NumLikeSelfType, other: NumLikeCastable) -> BoolExpr:  #type: ignore
-    return self._create_bool_op(self, self._to_expr_type(other), EqOp.ne)
+    if isinstance(other, self._CASTABLE_TYPES) or isinstance(other, self.__class__):
+      return self._create_bool_op(self, self._to_expr_type(other), EqOp.ne)
+    return NotImplemented
 
   def __gt__(self: NumLikeSelfType, other: NumLikeCastable) -> BoolExpr:  #type: ignore
-    return self._create_bool_op(self, self._to_expr_type(other), OrdOp.gt)
+    if isinstance(other, self._CASTABLE_TYPES) or isinstance(other, self.__class__):
+      return self._create_bool_op(self, self._to_expr_type(other), OrdOp.gt)
+    return NotImplemented
 
   def __ge__(self: NumLikeSelfType, other: NumLikeCastable) -> BoolExpr:  #type: ignore
-    return self._create_bool_op(self, self._to_expr_type(other), OrdOp.ge)
+    if isinstance(other, self._CASTABLE_TYPES) or isinstance(other, self.__class__):
+      return self._create_bool_op(self, self._to_expr_type(other), OrdOp.ge)
+    return NotImplemented
 
   def __lt__(self: NumLikeSelfType, other: NumLikeCastable) -> BoolExpr:  #type: ignore
-    return self._create_bool_op(self, self._to_expr_type(other), OrdOp.lt)
+    if isinstance(other, self._CASTABLE_TYPES) or isinstance(other, self.__class__):
+      return self._create_bool_op(self, self._to_expr_type(other), OrdOp.lt)
+    return NotImplemented
 
   def __le__(self: NumLikeSelfType, other: NumLikeCastable) -> BoolExpr:  #type: ignore
-    return self._create_bool_op(self, self._to_expr_type(other), OrdOp.le)
+    if isinstance(other, self._CASTABLE_TYPES) or isinstance(other, self.__class__):
+      return self._create_bool_op(self, self._to_expr_type(other), OrdOp.le)
+    return NotImplemented
 
 
 IntLike = Union['IntExpr', int]
 class IntExpr(NumLikeExpr[int, IntLike]):
+  _CASTABLE_TYPES = (int, )
+
   @classmethod
   def _to_expr_type(cls, input: IntLike) -> IntExpr:
     if isinstance(input, IntExpr):
@@ -287,6 +317,8 @@ def _from_lit(cls, pb: edgir.ValueLit) -> int:
 FloatLit = Union[float, int]
 FloatLike = Union['FloatExpr', float, int]
 class FloatExpr(NumLikeExpr[float, Union[FloatLike, IntExpr]]):
+  _CASTABLE_TYPES = (float, int)
+
   @classmethod
   def _to_expr_type(cls, input: Union[FloatLike, IntExpr]) -> FloatExpr:
     if isinstance(input, FloatExpr):
@@ -320,6 +352,9 @@ def max(self, other: FloatLike) -> FloatExpr:
 
 RangeLike = Union['RangeExpr', Range, Tuple[FloatLike, FloatLike]]
 class RangeExpr(NumLikeExpr[Range, Union[RangeLike, FloatLike, IntExpr]]):
+  # mypy doesn't like the unbounded tuple
+  _CASTABLE_TYPES = (float, int, FloatExpr, IntExpr, Range, tuple)  # type: ignore
+
   # Some range literals for defaults
   POSITIVE: Range = Range.from_lower(0.0)
   NEGATIVE: Range = Range.from_upper(0.0)
@@ -424,26 +459,6 @@ def _create_range_float_binary_op(cls,
     assert lhs._is_bound() and rhs._is_bound()
     return lhs._new_bind(BinaryOpBinding(lhs, rhs, op))
 
-  # special option to allow range * float
-  def __mul__(self, rhs: Union[RangeLike, FloatLike, IntLike]) -> RangeExpr:
-    if isinstance(rhs, (int, float)):  # TODO clean up w/ literal to expr pass, then type based on that
-      rhs_cast: Union[FloatExpr, IntExpr, RangeExpr] = FloatExpr._to_expr_type(rhs)
-    elif isinstance(rhs, (FloatExpr, IntExpr)):
-      rhs_cast = rhs
-    else:
-      rhs_cast = self._to_expr_type(rhs)  # type: ignore
-    return self._create_range_float_binary_op(self, rhs_cast, NumericOp.mul)
-
-  # special option to allow range / float
-  def __truediv__(self, rhs: Union[RangeLike, FloatLike, IntLike]) -> RangeExpr:
-    if isinstance(rhs, (int, float)):  # TODO clean up w/ literal to expr pass, then type based on that
-      rhs_cast: Union[FloatExpr, IntExpr, RangeExpr] = FloatExpr._to_expr_type(rhs)
-    elif isinstance(rhs, (FloatExpr, IntExpr)):
-      rhs_cast = rhs
-    else:
-      rhs_cast = self._to_expr_type(rhs)  # type: ignore
-    return self * rhs_cast.__mul_inv__()
-
   def shrink_multiply(self, contributing: RangeLike) -> RangeExpr:
     """RangeExpr version of Range.shrink_multiply.
     See docs for Range.shrink_multiply."""

edg/core/ConstraintExpr.py

@@ -144,9 +144,18 @@ def __contains__(self, item: Union['Range', float]) -> bool:
     else:
       return NotImplemented
 
+  def hull(self, other: 'Range') -> 'Range':
+    return Range(min(self.lower, other.lower), max(self.upper, other.upper))
+
   def intersects(self, other: 'Range') -> bool:
     return (self.upper >= other.lower) and (self.lower <= other.upper)
 
+  def intersect(self, other: 'Range') -> 'Range':
+    # TODO make behavior more consistent w/ compiler and returning empty that props as a unit
+    if not self.intersects(other):
+      raise ValueError("cannot intersect ranges that do not intersect")
+    return Range(max(self.lower, other.lower), min(self.upper, other.upper))
+
   def __add__(self, other: Union['Range', float]) -> 'Range':
     if isinstance(other, Range):
       return Range(self.lower + other.lower, self.upper + other.upper)

edg/core/Range.py

@@ -47,7 +47,7 @@ def test_ops(self) -> None:
 
     self.assertEqual(Range(1, 5).center(), 3)
 
-  def test_intersect(self) -> None:
+  def test_intersects(self) -> None:
     self.assertTrue(Range(-1, 2).intersects(Range(2, 3)))
     self.assertTrue(Range(-1, 2).intersects(Range(0, 3)))
     self.assertTrue(Range(-1, 2).intersects(Range(-2, -1)))
@@ -56,6 +56,22 @@ def test_intersect(self) -> None:
     self.assertFalse(Range(-1, 2).intersects(Range(3, 4)))
     self.assertFalse(Range(-1, 2).intersects(Range(-3, -2)))
 
+  def test_intersect(self):
+    self.assertEqual(Range(-1, 2).intersect(Range(2, 3)), Range(2, 2))
+    self.assertEqual(Range(-1, 2).intersect(Range(0, 3)), Range(0, 2))
+    self.assertEqual(Range(-1, 2).intersect(Range(-2, -1)), Range(-1, -1))
+    self.assertEqual(Range(-1, 2).intersect(Range(-2, 0)), Range(-1, 0))
+    self.assertEqual(Range(-1, 2).intersect(Range(0, 1)), Range(0, 1))
+    with self.assertRaises(ValueError):
+      Range(-1, 2).intersect(Range(3, 4))
+
+  def test_hull(self):
+    self.assertEqual(Range(-1, 2).hull(Range(2, 3)), Range(-1, 3))
+    self.assertEqual(Range(-1, 2).hull(Range(0, 3)), Range(-1, 3))
+    self.assertEqual(Range(-1, 2).hull(Range(-2, -1)), Range(-2, 2))
+    self.assertEqual(Range(-1, 2).hull(Range(-2, 0)), Range(-2, 2))
+    self.assertEqual(Range(-1, 2).hull(Range(0, 1)), Range(-1, 2))
+
   def test_shrink_property(self) -> None:
     range1 = Range(10, 20)
     self.assertEqual(range1.shrink_multiply(1/range1), Range(1, 1))

edg/core/test_range.py

@@ -279,7 +279,7 @@
   (value "4.1A 4.7uH ±30% 23.4mΩ SMD,8x8x4.2mm Power Inductors ROHS")
   (footprint "Inductor_SMD:L_Taiyo-Yuden_NR-80xx")
   (property (name "Sheetname") (value "power_path"))
-  (property (name "Sheetfile") (value "edg.abstract_parts.AbstractPowerConverters.BuckConverterPowerPath"))
+  (property (name "Sheetfile") (value "examples.test_fcml.FcmlPowerPath"))
   (property (name "edg_path") (value "conv.power_path.inductor"))
   (property (name "edg_short_path") (value "conv.power_path.inductor"))
   (property (name "edg_refdes") (value "L2"))

examples/Fcml/Fcml.net

@@ -279,7 +279,7 @@
   (value "4.1A 4.7uH ±30% 23.4mΩ SMD,8x8x4.2mm Power Inductors ROHS")
   (footprint "Inductor_SMD:L_Taiyo-Yuden_NR-80xx")
   (property (name "Sheetname") (value "power_path"))
-  (property (name "Sheetfile") (value "edg.abstract_parts.AbstractPowerConverters.BuckConverterPowerPath"))
+  (property (name "Sheetfile") (value "examples.test_fcml.FcmlPowerPath"))
   (property (name "edg_path") (value "conv.power_path.inductor"))
   (property (name "edg_short_path") (value "conv.power_path.inductor"))
   (property (name "edg_refdes") (value "L2"))

examples/Fcml/Fcml.ref.net

@@ -276,14 +276,14 @@
   (sheetpath (names "/pwr/fb/") (tstamps "/02b3015a/013000c9/"))
   (tstamps "175b043f"))
 (comp (ref "pwr.power_path.inductor")
-  (value "390mA 47uH ±10% 1Ω 1210 Power Inductors ROHS")
+  (value "250mA 33uH ±10% 800mΩ 1210 Inductors (SMD) ROHS")
   (footprint "Inductor_SMD:L_1210_3225Metric")
   (property (name "Sheetname") (value "power_path"))
   (property (name "Sheetfile") (value "edg.abstract_parts.AbstractPowerConverters.BoostConverterPowerPath"))
   (property (name "edg_path") (value "pwr.power_path.inductor"))
   (property (name "edg_short_path") (value "pwr.power_path.inductor"))
   (property (name "edg_refdes") (value "L1"))
-  (property (name "edg_part") (value "BRL3225T470K (Taiyo Yuden)"))
+  (property (name "edg_part") (value "CMI322513J330KT (FH(Guangdong Fenghua Advanced Tech))"))
   (sheetpath (names "/pwr/power_path/") (tstamps "/02b3015a/1786043a/"))
   (tstamps "0f2b0369"))
 (comp (ref "pwr.power_path.in_cap")

examples/Simon/Simon.net

@@ -276,14 +276,14 @@
   (sheetpath (names "/pwr/fb/") (tstamps "/02b3015a/013000c9/"))
   (tstamps "175b043f"))
 (comp (ref "L1")
-  (value "390mA 47uH ±10% 1Ω 1210 Power Inductors ROHS")
+  (value "250mA 33uH ±10% 800mΩ 1210 Inductors (SMD) ROHS")
   (footprint "Inductor_SMD:L_1210_3225Metric")
   (property (name "Sheetname") (value "power_path"))
   (property (name "Sheetfile") (value "edg.abstract_parts.AbstractPowerConverters.BoostConverterPowerPath"))
   (property (name "edg_path") (value "pwr.power_path.inductor"))
   (property (name "edg_short_path") (value "pwr.power_path.inductor"))
   (property (name "edg_refdes") (value "L1"))
-  (property (name "edg_part") (value "BRL3225T470K (Taiyo Yuden)"))
+  (property (name "edg_part") (value "CMI322513J330KT (FH(Guangdong Fenghua Advanced Tech))"))
   (sheetpath (names "/pwr/power_path/") (tstamps "/02b3015a/1786043a/"))
   (tstamps "0f2b0369"))
 (comp (ref "C4")